In a small seaside town, two best friends, Claire and Hailey, are dealing with the inevitable changes that summer brings. With the arrival of vacation, they realize that this could be their last summer together, as Hailey is moving to another state. Everything seems lost until one day, while exploring a beach cabin, they encounter a mysterious being: a mermaid named Aquamarine.
The young mermaid, who has escaped from her life in the ocean, reveals that she has come to the surface to prove that true love exists. Desperate not to say goodbye and to reignite the magical spark of friendship, Claire and Hailey decide to help her in her mission. Their plan involves Aquamarine finding the love of a human before summer ends, and the target turns out to be a handsome local boy, who also has some connection to both of them.
With a mix of laughter, tears, and unforgettable moments, the three young women face the ups and downs of adolescence, discovering not only the true meaning of friendship but also the sacrifices and decisions that come with growing up. As emotions intensify, the girls' expectations are put to the test, and they must learn that sometimes letting go is part of life. This magical and enchanting adventure reveals that, despite distance, bonds can endure forever.